Patent GB-727565-A (GB)
Title: Recovery of organic nitrogenous compounds
Inventor: SKINNER LOUIS GORDON
IPC: B01J47/00
Filed: 1950-10-13
Abstract: Organic nitrogenous compounds which are defined as betaine and basic amino acids are recovered from a crude dilute aqueous solution thereof by passing the solution through a column of a cation exchange material on which constituents of the solution other than the organic nitrogenous compounds, for example inorganic cations, are preferentially adsorbed and passing the effluent, which contains an increased proportion of the organic nitrogenous compounds, into a second column of a cation exchange material on which the organic nitrogenous compounds are adsorbed and then eluting the adsorbed organic nitrogenous compounds from the second column, the passing of the solution being discontinued if the first column becomes saturated with the preferentially adsorbed constituents.  The process is particularly suitable for the recovery of betaine from yeast waste solutions containing inorganic cations.  Suitable eluting agents for elution of the adsorbed organic nitrogenous compounds include aqueous potassium chloride, aqueous ammonium chloride, aqueous hydrochloric acid and preferably aqueous ammonia-suitably of 10 per cent strength. The cation exchange material employed may be an inorganic type material, but is preferably an organic type such as one of the sulphonated coal type cation exchange materials, e.g. "Zeo-Karb HIT" or a cation exchange resin, e.g. "Zeo-Karb 215," "Zeo-Karb 315" and "Amberlite IR 105" (the words "Zeo-Karb" and "Amberlite" are Registered Trade Marks).  The invention may be carried out by arranging two columns of cation exchange material in series, the head of the first column being fed with the crude aqueous solution and the head of the second column with the effluent or percolate from the first column.  When the first column is saturated with inorganic cations it is isolated from the second column and regenerated and the process continued until the second column is saturated with betaine as is indicated by the appearance of betaine in the effluent from the second column which is normally marked by a rise in the pH of the effluent. Regeneration of the first column may be effected with an aqueous solution of a mineral acid or ammonia.  In the case of yeast wash in which the chief inorganic ion present is potassium, the regeneration of the first column may be effected by eluting with aqueous ammonium sulphate, giving a mixed potassium-ammonium sulphate eluate solution which is of value as a fertilizer, and then treating the column with a mineral acid.  The process may be carried out in a continuous manner by replacing the original first column when saturated with a duplicate column which is used whilst the first column is being regenerated.  The relative capacities of the two columns for the ions to be adsorbed may be substantially equal so that the appearance of inorganic cations in the effluent from the first column occurs at the same time as the appearance of the organic nitrogenous compound in the effluent from the second column.  The fractions of the eluate of the second column which have a small betaine content, e.g. less than 25 grams per litre, may be re-used for the elution of a subsequent column saturated with betaine.  The organic nitrogenous compound may be recovered from the eluate containing it by evaporation and may be further purified by extraction with an organic solvent such as ethyl alcohol.  If eluting media such as aqueous potassium chloride or hydrochloric acid are used, the organic nitrogenous compound may be obtained in the form of the corresponding salt from which it may be liberated by treatment with alkali.  Three examples are given for the recovery of butaine in the form of its hydrochloride from yeast waste solutions.  In each case the two columns are connected in series and when the pH of the effluent from the first column reaches 4 the column is regenerated and the flow of yeast wash through the two columns is then resumed until betaine is observed in the effluent from the second column. The two columns are then isolated and the first column regenerated and washed whilst the second column is eluted and the eluate treated for the recovery of betaine hydrochloride.  In (1) "Zeo-Karb 215" is used in both columns, the first column is regenerated with 20 per cent hydrochloric acid and finally washed with distilled water whilst the second column after washing with distilled water is eluted with 10 per cent aqueous ammonia, washed with decationised slightly acid water regenerated with 20 per cent hydrochloric acid and washed with distilled water until neutral.  In (2) the two columns have the same cation exchange material as in (1), the first column is regenerated with 10 per cent sulphuric acid and the second column eluted with 20 per cent hydrochloric acid.  In (3) the first column contains "Zeo-Karb 215" and the second contains "Zeo-Karb 315."  The first column is regenerated with hydrochloric acid and the second column is eluted with 10 per cent ammonia and regenerated with aqueous hydrochloric acid.  The eluate from the second column is collected in fractions and the exhaustion cycle repeated.  The second column is eluted with the eluate fractions having a betaine content of less than 3 per cent followed by 10 per cent ammonia and is finally regenerated with aqueous hydrochloric acid, the cycle of operations being repeated until a sufficient quantity of betaine rich eluate solution is obtained.